Event Notification Report for December 28, 2001
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
12/27/2001 - 12/28/2001
EVENT NUMBERS
38650
Power Reactor
Event Number: 38650
Facility: PILGRIM
Region: 1 State: MA
Unit: [1] [] []
RX Type: [1] GE-3
NRC Notified By: ERIC OLSON
HQ OPS Officer: BOB STRANSKY
Region: 1 State: MA
Unit: [1] [] []
RX Type: [1] GE-3
NRC Notified By: ERIC OLSON
HQ OPS Officer: BOB STRANSKY
Notification Date: 01/25/2002
Notification Time: 15:36 [ET]
Event Date: 12/28/2001
Event Time: 17:01 [EST]
Last Update Date: 01/25/2002
Notification Time: 15:36 [ET]
Event Date: 12/28/2001
Event Time: 17:01 [EST]
Last Update Date: 01/25/2002
Emergency Class: NON EMERGENCY
10 CFR Section:
50.73(a)(1) - INVALID SPECIF SYSTEM ACTUATION
10 CFR Section:
50.73(a)(1) - INVALID SPECIF SYSTEM ACTUATION
Person (Organization):
PETE ESELGROTH (R1)
PETE ESELGROTH (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Cold Shutdown | 0 | Cold Shutdown |
60-DAY OPTIONAL REPORT PURSUANT TO 10CFR50.73(a)(1)
"On 12/28/01, the plant was in a cold shutdown condition with the RHR system in the shutdown cooling mode. The reactor head vent valves were open.
"At 1701 hours a reactor water level indication spike (notching) occurred on the 'B' narrow range reactor water level instrumentation (e.g. instrument rack C-2206). The event occurred when Reactor Recirculation Pump 'B' was started. This resulted in Reactor Pressure Vessel pressure lowering due to condensing of vapor in the Reactor Vessel. The spiking was due to gasses coming out of solution in the reference leg associated with the 'B' narrow range instruments. The specific source of the gas is still under investigation. No spike was noted on the 'A' narrow range reactor water level instrumentation (e.g. instrument rack C-2205). The Group I isolation resulted in the closure of the Reactor Water Sample valves (AQ-44 and AQ-45). The Main Steam Isolation Valves (MSIV's) were already closed due to plant conditions.
"The Group I isolation was the result of a false high water level signal(s) from analog trip system trip units LS-263-58A-2 (to PCIS Channel A2) and LS-263-58B-2 (to PCIS Channel B2) while the reactor mode switch was in the REFUEL position (not RUN). A Group I isolation is designed to occur if a high water level condition occurs when the reactor mode switch is not in the RUN position. These trip units receive signals from reactor water level transmitters LT-263-58A (instrument rack 2206A) and LT-263-58B (instrument rack 2206A) that are associated with condensing chamber 12B.
"The Group I isolation signal was not valid because a reactor water level increase of about 20" did not actually occur. Thus, even though the Group I isolation signal was not planned, the isolation signal was invalid."
The NRC resident inspector has been informed of this report by the licensee.
"On 12/28/01, the plant was in a cold shutdown condition with the RHR system in the shutdown cooling mode. The reactor head vent valves were open.
"At 1701 hours a reactor water level indication spike (notching) occurred on the 'B' narrow range reactor water level instrumentation (e.g. instrument rack C-2206). The event occurred when Reactor Recirculation Pump 'B' was started. This resulted in Reactor Pressure Vessel pressure lowering due to condensing of vapor in the Reactor Vessel. The spiking was due to gasses coming out of solution in the reference leg associated with the 'B' narrow range instruments. The specific source of the gas is still under investigation. No spike was noted on the 'A' narrow range reactor water level instrumentation (e.g. instrument rack C-2205). The Group I isolation resulted in the closure of the Reactor Water Sample valves (AQ-44 and AQ-45). The Main Steam Isolation Valves (MSIV's) were already closed due to plant conditions.
"The Group I isolation was the result of a false high water level signal(s) from analog trip system trip units LS-263-58A-2 (to PCIS Channel A2) and LS-263-58B-2 (to PCIS Channel B2) while the reactor mode switch was in the REFUEL position (not RUN). A Group I isolation is designed to occur if a high water level condition occurs when the reactor mode switch is not in the RUN position. These trip units receive signals from reactor water level transmitters LT-263-58A (instrument rack 2206A) and LT-263-58B (instrument rack 2206A) that are associated with condensing chamber 12B.
"The Group I isolation signal was not valid because a reactor water level increase of about 20" did not actually occur. Thus, even though the Group I isolation signal was not planned, the isolation signal was invalid."
The NRC resident inspector has been informed of this report by the licensee.